Prototype paused admin participant AI support

Enable an existing AI difficulty for a human seat through admin controls without granting private access or advancing paused play. Preserve custody, credentials, takeback and separate paced resume. Bind atomic writes and outgoing-grant revocation to live authority, room/pause versions and active seat access with durable exact receipts.

Validation: types/lint, 5408 offline tests, build and 52 HTTP tests passed on source fingerprint 2157de0f4bb0b74d9760d52102601c52344cf674dee8ccd1d559f0a246a1d4ff; 22 authenticated admin HTTP groups, independent SQL/privacy/UI review, desktop/mobile and refresh checks. All 2098 baseline rooms and 4455 seats preserved. Migration 0015 is additive. Positive production admin QA awaits authorized access; full admin/rules scope remains unfinished.

drizzle/0015_admin_seat_ai.sql

@@ -0,0 +1,15 @@
+CREATE TABLE `admin_seat_ai_operations` (
+	`operation_id` text PRIMARY KEY NOT NULL,
+	`actor_admin_id` text NOT NULL,
+	`room_code` text NOT NULL,
+	`request_hash` text NOT NULL,
+	`expected_version` integer NOT NULL,
+	`expected_control_revision` integer NOT NULL,
+	`applied_version` integer NOT NULL,
+	`target` text NOT NULL,
+	`difficulty` text NOT NULL,
+	`reason` text NOT NULL,
+	`created_at` integer NOT NULL
+);
+--> statement-breakpoint
+CREATE INDEX `admin_seat_ai_room` ON `admin_seat_ai_operations` (`room_code`,`created_at`);

drizzle/meta/_journal.json

@@ -106,6 +106,13 @@
       "when": 1790044461950,
       "tag": "0014_admin_room_archive",
       "breakpoints": true
+    },
+    {
+      "idx": 15,
+      "version": "6",
+      "when": 1790389395436,
+      "tag": "0015_admin_seat_ai",
+      "breakpoints": true
     }
   ]
 }